Method of controlling the cooling rate of narrow side walls of plate molds as a function of the casting taper during continuous casting

ABSTRACT

A method of controlling the cooling rate of narrow side walls of plate molds during continuous casting, wherein the narrow side walls are fixedly clamped between the wide side walls, prior to start of the casting the hollow casting compartment between the narrow side walls is provided with a casting taper which converges in the direction of travel of the cast strand or casting and which is accommodated to the quality of the steel and the width of the strand. Prior to the start of the casting operation the casting taper is additionally adjusted to a reference value which corresponds to the contemplated casting speed and/or casting temperature, and upon deviation of the casting speed and/or casting temperature during the casting operation the casting taper is changed in accordance with reference values corresponding to such fluctuating or changing casting parameters.

United States Patent [191 Meier et al.

[ Dec. 16, 1975 METHOD OF CONTROLLING THE COOLING RATE OF NARROW SIDEWALLS OF PLATE MOLDS AS A FUNCTION OF THE CASTING TAPER DURINGCONTINUOUS CASTING [75] Inventors: Walter Meier, Winterthur; JosefZeller, Weesen; Peter J. Koenig, Zumikon; Werner Bruderer,

Feldmeilen; Markus Schmid, Zurich, all of Switzerland [73] Assignee:Concast AG, Zurich, Switzerland [22] Filed: Mar. 25, 1974 [21] Appl.No.: 454,682

[30] Foreign Application Priority Data 12/1966 Colombo 164/273 R XPrimary ExaminerR. Spencer Annear Attorney, Agent, or FirmWerner W.Kleeman [5 7] ABSTRACT A method of controlling the cooling rate ofnarrow side walls of plate molds during continuous casting, wherein thenarrow side walls are fixedly clamped between the wide side walls, priorto start of the casting the hollow casting compartment between thenarrow side walls is provided with a casting taper which converges inthe direction of travel of the cast strand or casting and which isaccommodated to the quality of thesteel and the width of the strand.Prior to the start of the casting operation the casting taper isadditionally adjusted to a reference value which corresponds to thecontemplated casting speed and/or casting temperature, and upondeviation of the casting speed and- /or casting temperature during thecasting operation the casting taper is changed in accordance withreference values corresponding to such fluctuating or changing castingparameters.

15 Claims, 6 Drawing Figures US. Patent Dec. 16,1975 Sheet 1of33,926,244

Fig.1

US. Patent Dec. 16, 1975 Sheet2of3 3,926,244

Fig.3

US. Patent Dec. 16, 1975 Sheet 3 of 3 3,926,244

Fig. 5

METHOD OF CONTROLLING THE COOLING RATE OF NARROW SIDE WALLS OF PLATEMOLDS AS A FUNCTION OF THE CASTING TAPER DURING CONTINUOUS CASTINGBACKGROUND OF THE INVENTION The present invention relates to a new andimproved method of controlling the cooling rate of narrow side walls ofplate molds during continuous casting, wherein the narrow side walls arefixedly clamped between wide side walls of the mold, prior to the startof the casting operation the hollow mold compartment between the narrowside walls is provided with a casting taper which converges in thedirection of travel of the strand and which is accommodated to thequality of the cast metal, typically steel, and the width of the strand,and furthermore, the invention also pertains to a new and improvedapparatus for the performance of the aforesaid method.

During the continuous casting of steel there is strived for as uniformas possible withdrawal of heat at all sides of the cast strand withinthe mold, in order that the strand, upon departure from the mold,possesses at all sides as uniform as possible thickness of the strandshell or skin.

Owing to differences in the contraction of the strand shell at thenarrow and wide sides of the mold, governed by the shape or format ofthe casting or cast strand, it has been found during casting of slabsthat the surface of the strand does not bear in the same manner againstthe narrow and wide side walls of the mold. Additionally, contact of thesolidified shell of the strand against the walls of the mold can beinfluenced by the phenomenon of the mold bulging or bowing-out,particularly the wide sides of the mold. It is conventional 'practice toprovide the narrow sides of the hollow mold compartment with a castingtaper which converges in the direction of the outlet end of the mold andto design the wide sides of the hollow mold compartment so as to beparallel or to possess a casting taper which differs in relation to thenarrow sides of the mold.

Additionally, this particular field of technology is aware of anadjustable plate mold construction which, along with the adjustment ofthe narrow sides of the mold to different widths of the strand,simultaneously alters the casting taper of the hollow mold compartmentbetween such walls according to a value of the contraction of the strandwhich is predetermined as a function of the width of the strand. Theadjusted casting taper or cone, however, is only optimum for a smallrange of the casting speed and the casting temperature, i.e., contact ofthe solidified strand shell and thus the withdrawn quantity of heat isonly optimum at such values. Upon changing the casting speed and/or thecasting temperature the shrinkage or contraction also alters, andconsequently, there results non-uniform cooling and solidification ofthe shell or skin of the strand. These irregularities lead to fissuresand ruptures and increase the breakout danger and wear of the mold.

A further proposal which has been advanced in the an concerns a platemold which is subdivided into two components transversely with regard tothe direction of travel of the strand. The upper portion does notpossess any casting taper and the walls of the lower portion areresiliently urged against the strand surface. Gaps are provided betweenthe walls arranged at the lower portion which neighbor one another,rendering possible free movement of the walls without mutual hindrance.The resilient or spring force which acts against such walls must becapable, on the one hand, of withstanding the force generated by theferrostatic pressure and, on the other hand, the resilient force mustnot deform the strand shell which is still thin. This prior artequipment is unsuitable for casting operations where there prevailfluctuating casting parameters, such as casting speed and castingtemperature and the like, because the resilient or spring force is notadjustable to different thicknesses or different strengths of the shell.Moreover, walls which are pressed against one another by such springstend to wear rapidly. Additionally, such narrow side walls of the moldcannot be fixedly clamped between the wide side walls of the mold, sothat at the region of the level of the molten bath there is precludedthe use of such equipment.

Apart from the foregoing proposals there is also known in the art anapparatus for adjusting the format or shape of a plate mold when thecasting operation is not in progress, wherein initially the narrow sidewalls of the mold are shifted without changing the casting taper andfixed in position in accordance with the desired shape or format of thestrand to be cast, and subsequently the casting taper is adjusted to thedesired extent. With this apparatus there is not present during thecasting operation uniform cooling of the cast strand with changingcasting parameters.

SUMMARY OF THE lNVENTlON Hence, it will be recognized that in thisparticular field of technology there is still need for a method of, andapparatus for, controlling the cooling capacity of narrow side walls ofplate molds during continuous casting in a manner not associated withthe aforementioned drawbacks and limitations of the prior art proposals.Consequently, it is a primary object of the present invention to providean improved method of controlling the cooling capacity or efficiency ofnarrow side walls of plate molds during continuous casting in a mannerfulfilling the need existing in the art.

Another and more specific object of the invention aims at providing animproved method of carrying out continuous casting operations whileproviding optimum and uniform cooling within the mold during changes inthe casting parameters, in particular the casting speed and the castingtemperature.

Another object of the invention is directed at rendering possiblecontinuous casting operations, particularly at high output continuouscasting installations, with large differences in the casting speed andwhile providing improved quality in the cast strand and reducing thedanger of metal breakout.

Now in order to implement these and still further objects of theinvention, which will become more readily apparent as the descriptionproceeds, the method aspects of this development are manifested by thefeatures that prior to the start of the casting operation the castingtaper is additionally adjusted to a reference value corresponding to theprescribed casting speed and/or casting temperature, and upon deviationof the casting speed and/or the casting temperature during the castingoperation the casting taper is altered in accordance with predeterminedreference values which produce a desired or optimum cooling effectcorresponding to such fluctuating casting parameters.

When using this technique it is possible to provide optimum coolingconditions at the plate molds at the narrow sides of the strand, even inthe presence of markedly varying casting speeds, casting temperaturesand so forth. Consequently, in the case of continuous castinginstallations for slabs operating at high casting speeds, for instancein the order of about 2 meters per minute, there is present thepossibility, during the same pour, to also work at a casting speed rangebeneath 1 meter per minute with a predetermined cooling rate and to caststrands possessing optimum quality and without increased risk ofbreakout. There are many reasons for casting with different castingspeeds at such installations. By way of example it is mentioned: slowstart of the casting operation, disturbances in the flow of metalbetween the tundish and the mold or between the ladle and tundishrespectively, accommodation of the casting time to the operating cycleof the converter, reduced casting speed at the end of the castingoperation, and so forth.

The accommodation of the casting taper during or shortly after thechange of the casting speed, the casting temperature or other castingparameters which influence solidification of the strand, can be carriedout according to different techniques. Thus, it is possible, forinstance, to determine an optimum reference value of the taper orconicalness between the narrow sides of the moldwalls as a function ofthe casting speed and/or the casting temperature by empirical tests.Such optimum reference value, as a general rule, is strived for inrespect of uniform solidification of the shell of the strand. Thecasting taper can be accommodated to predetermined reference valuescorresponding to the altered casting speed and/or the altered castingtemperature. Reference values for the casting taper K in the continuouscasting art are normally expressed in terms of percent per meter per m).

It is further possible to use a desired reference cooling rate of thenarrow side walls as the basic value for the adjustment of the taper.Both the casting temperature as well as also the casting speed arecasting parameters which influence the cooling rate of the mold walls.According to a further aspect of theinvention, the cooling rate of thenarrow side walls of the mold can be continuously measured, suchmeasurement values compared with those reference cooling rate valuescorresponding to the actual-casting speed and/or the actual-castingtemperature and upon deviation between the referenceand actualcoolingrate values adjusting the casting taper until reaching the referencecooling rate. The cooling rate of the narrow side walls of the mold, notonly is influenced by the casting speed and the casting temperature, butalso by the flow at the liquid casting head, the nature and quantity ofthe casting powder slag and by bending moments produced by virtue ofirregular .cooling of the strand.

. A further advantageous method for accommodating the casting taperduring change of a casting parameter influencing the cooling rate ofthe. narrow side walls of the mold can be realized according to theinvention if the specific cooling rate of the narrowand the wide sidewalls are continuously measured, the measurement values of the narrowandwide side walls mutually compared and the specific actual-cooling rateratio between such walls discriminated with the predetermined specificreference-cooling rate ratio and. upon deviation between thespecificreference-' and actual-cooling rate ratio accommodating the castingtaper until reaching the specific reference-cooling rate ratio.According to this technique the withdrawal of heat at the strand and thegrowth of the strand shell is controlled as a function of the sum of thecasting parameters which are responsible therefor. At the same time allcasting parameters and also all uncontrollable influencing factors, suchas expansion within the mold or the bending moments at the strandgenerated by the secondary cooling and so forth, are taken into account.

The reference taper, for given casting parameters, can be advantageouslyascertained during the casting operation if the cooling rate of thenarrow side walls of the mold is continuously measured, during change ofthe casting taper K there is differentiated the deviation of the coolingrate AQ (Kcal/cm sec) according to the deviation of the taper AK (%/m)and the reference taper associated with the reference cooling rate valuedetermined from the curve characteristic. As a general rule, thereference cooling rate value and the reference taper is located at thetransition region between the ascending and horizontal branch of thefunction curve Q/ Q- In order that there can be minimally selected theforce for adjusting the casting taper of the hollow mold compartmentbetween the narrow side walls during a continuous pour or casting and inorder to be able to produce slabs according to desired dimension fordifferent casting speeds as well as ensuring that at the same time thereis not necessary any adjustment of the strand guide assembly whichimmediately follows the mold, it is possible, according to a furtherfeature of the invention, during accommodation or adjustment of thecasting taper, to maintain the size of the hollow mold compartment,corresponding to the rated size of the strand, at the output of the moldbetween the narrow mold walls. In this regard, as a general rule, themold is designed such that the pivotable connection associated with theplates for the adjustment of the taper is formed by a shaft extendingparallel to the narrow side walls of the mold, and which shaft islocated near to a plane formed by the outlet of the mold.

The force for adjusting the casting taper during the casting operationcan be maintained relatively small and there can be avoided scratchingof the copper plates of the wide side walls of the mold if, according toan additional facet of the invention, the force for fixedly clamping thenarrow side walls during the adjustment operation is reduced to abouttwice the value of the counter-force which acts by virtue of theferrostatic pressure and after the adjustment again increased to thevalue which prevailed prior to the adjustment.

Not only is the invention concerned with the aforementioned methodaspects, but as already heretofore mentioned, also deals with a new andimproved construction of apparatus for the performance thereof, andspecifically a plate mold wherein the narrow side walls of the moldwhich can be fixedly clamped between the wide side walls of the mold areequipped with devices for adjusting the hollow mold compartment todifierent strand dimensions and with devices for adjusting the castingtaper. Between the support or carrier frame and the narrow side walls ofthe mold there is arranged a plate which is pivotably connected, andthat alternately the one of both adjustment devices is attached to thesupport frame and. to the plate and the other of the adjustment devicesis connected to the plate and the narrow side wall.

The clamping force of the wide side walls can remain unchanged duringthe accommodation of the casting taper to the different castingparameters and at the same time there can be avoided wear of the copperplates at the wide side walls of the mold if, according to a furtheraspect of the invention, the taper adjustment device is attached to theplate and at the narrow side wall and the apparatus for adjusting thehollow mold compartment to different strand dimensions is attached tothe plate and at the carrier or support frame, wherein the plateconnected by the shaft with the narrow side wall can be clamped betweenthe wide side walls, and if the size of the plate which determines thewidth of the hollow mold compartment is greater up to two millimeters inrelation to the narrow side wall.

A further advantageous mold construction of the invention is manifestedby the features that the taper adjustment device is secured to the plateand at the carrier frame, the device for adjusting the hollow moldcompartment to different strand dimensions is secured to the plate andto the narrow side wall, and that the plate together with the narrowside wall is pivotable about the shaft arranged at the carrier frame.

BRIEF DESCRIPTION OF THE DRAWINGS IIII thereof;

FIG. 3 is a plan view of a further embodiment of a partially illustratedplate mold designed according to the invention;

FIG. 4 is a cross-sectional view of the arrangement depicted in FIG. 3,taken substantially along the line IVIV thereof;

FIG. 5 is a schematic illustration of a plate mold equipped with acontrol device; and

FIG. 6 is a diagram portraying the cooling rate as a function of thecasting taper.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now thedrawings, in FIGS. 1 and 2 reference character 1 designates a plate moldfor the contin uous casting of metals, typically steel. A stationarywide side wall 2 and a movable wide side wall 2 of the mold as well asthe narrow side walls 3 (only one of which is visible in FIG. 1) delimita hollow mold compartment or cavity 4. Each narrow side wall 3 of themold consists of a copper plate 7. confronting the hollow moldcompartment 4 and a support plate 8. The walls 2, 2, 3 are supported ata support or carrier frame 5 which extends about the mold 1. Owing tothe action of the force generated by a pistoncylinder unit 6 the narrowside walls 3 of the mold 1 are fixedly clamped between the wide sidewalls 2, 2' thereof.

In order to adjust the hollow mold compartment 4 to different stranddimensions there is secured to each narrow side wall 3 and to a plate 17a device consisting of a spindle l1 and an adjustment drive or gearing12 which cooperates with such spindle 11. The spindle 11 is hingedlyconnected with the associated narrow side wall 3 by means of a bolt 14or equivalent. The adjustment drive 12 is secured to the plate 17 which,in turn,

is connected by means of a hinge or pivot means 16 with the carrier orsupport frame 5. Between the pivotal plate 17 and the narrow side wall 3there are suspended insertable format-dependent support gauges 20.

Now in order to be able to adjust the casting taper or cone duringcasting a taper adjustment device is arranged at the plate 17 and at thecarrier or support frame 5. A spindle 21 cooperates with an adjustmentdrive or gearing 22 which is secured to the support frame 5. Duringmovement of the spindle 21, the plate 17 together with the narrow sidewall 3 is rocked about a shaft or axle 25 which extends transverse tothe direction of travel 24 of the casting or strand and parallel to thenarrow side walls 3. The shaft 25 is arranged near the plane 27 formedby the outlet or discharge end of the mold l, and the adjustment driveor gearing 22, viewed in the direction of travel 24 of the strand, isarranged in front of or forwardly of such shaft 25. By virtue of thisarrangement of the shaft 25 there can be achieved the beneficial resultthat, during adjustment of the casting taper during the castingoperation by means of the adjustment drive 22, there can be practicallymaintained the dimensions or size 28, associated with the rated size ordimensions of the strand, of the hollow mold compartment 4 at the outletend of the mold between the narrow sides or side walls 3. The adjustmentdrives 12 and 22 are; equipped, for instance, with not particularlyillustrated electrical devices. Other adjustment devices, for instancehydraulic adjustment devices, could be equally used.

In FIGS. 3 and 4 there is illustrated a different solution. Theconstruction of the mold with regard to the support or carrier frame 5,the therein supported wide side walls 2, 2 and the piston-cylinder unit6 are the same as considered above with regard to the description ofFIGS. 1 and 2.

In order to adjust the hollow mold compartment 4 with regard to thewidth of the casting or strand there is connected, on the one hand, aspindle 32 with a plate 31 and, on the other hand, with the carrier orsupport frame 5. This spindle 32 can be driven by means of an adjustmentdrive or gearing 33. The adjustment drive 33 is secured to the supportframe 5. Between the plate 31 and the support frame 5 there aresuspended the format-dependent adjustmentand support gauges 20. Anadjustment drive or gearing 35 is connected with the plate 31, and whichadjustment drive cooperates with a spindle 36 and serves for adjustingthe taper of the hollow mold compartment 4 between the narrow side walls3 of the mold. In so doing, the associated narrow side wall 3 is rockedor pivoted about a shaft or axle 37. The center line of the shaft 37 islocated at the mold outlet plane 27. The shaft 37 hingedly connects thenarrow side wall 3 with the plate 31 arranged between the narrow sidewall 3 and the support frame 5. The dimension 38 of the clamping wall 31and which dimension determines the width of the hollow mold compartmentis larger, in contrast to the narrow side wall 3, by as much as up totwo millimeters.

The clamping force generated by the piston-cylinder unit 6 is thuscompletely taken-up by the plate 31 in the cold condition of the mold.Due to heating of the copper plate 7 during the casting operation thereis closed gap 39, especially at the region of the molten metal bath,which is present in the cold state of the mold. In order to preventpenetration of steel spatters or the like into the gap 39 during thestart of the casting operation,

7 the joints can be covered by means of adhesive tapes or bands. Withthis solution rocking or pivoting of the narrow side walls 3 during thecasting operation can be accomplished with slight force and withoutchanging the contact force of the piston-cylinder units 6.

Turning attention now to FIG. 5 reference numeral 50 designates a platemold for slabs which, as already described, essentially comprises bothof the wide side walls 2, 2 and both of the narrow side walls 3, 3. Themold walls possess cooling chambers or compartments 63-70 whichencompass given cooling regions. In order to simplify the showing of thedrawings the cooling chambers have not been subdivided in the directionof travel of the strand. If desired the cooling rate can bedifferentially measured and evaluated by subdividing the coolingchambers transversely with respect to the direction of travel of thestrand. Each cooling chamber 63-70 is equipped with water infeedandoutfeed lines or conduits 72. Measuring elements 59 are connected withthe water infeedand outfeed lines 72 of the wide sides 2, 2 of the moldfor determining the quantity of withdrawn heat and the cooling rate. Ateach of the measuring elements 59 there is simultaneously formed anaverage or mean value of the cooling rate of the cooling chambers 63,64, and 65, 66 respectively, which are delivered to an average valueforming device 55. The cooling rate of both cooling chambers 67, 68 and69, 70 of the narrow side walls 3, 3 are measured at the measuring ormeasurement elements 51 and 51 respectively, and delivered as average ormean values 52 and 52 to the difference or differential value formingdevices 53, 54 and 53, 54 respectively. The differential value formingdevices 53, 53 furthermore have delivered thereto an output signal 74emanating from the average or mean value forming device 55. Thedifferential value forming devices 53, 53 generate differential valuesignals 56, 56' respectively, which correspond to the difference betweenthe cooling rate of the corresponding narrow sides and wide sides of themold. These signals 56, 56' are delivered to a computer 58. Thedifferential value forming devices 54, 54 generate differential valuesignals 57, 57 resulting from the actual-cooling rates of the narrowsides and a signal 73 for the predetermined reference-cooling rate ofthe narrow sides and which reference-cooling rate is correlated to orassociated with the actual-casting speed and/or the actual-castingtemperature. The computer 58 can selectively control mechanicaladjustment or setting elements 60, 60' for the adjustment of the taperof the narrow sides of the mold either as a function of the signals 56,56 or the signals 57, 57'. If the adjustment elements 60, 60' arecontrolled as a function of the signals 56, 56', then by changing thecasting taper the cooling rate of the narrow side walls is continuouslyadjusted to a predetermined cooling rate ratio between the narrow andwide side walls of the mold. Consequently, there is attainable a uniformcooling rate ratio or relationship between the narrowand wide sides ofthe mold. With this method it is possible that there prevails adifferential value 57, 57' in relation to a predeterminedreference-cooling rate value of the narrow sides of the mold and whichis accommodated to the casting speed, etc. If the adjustment elements60, 60 are controlled in accordance with the signals 57, 57', thenindependent of the cooling rate of the wide sides of the mold there iscontinuously measured the cooling rate of the narrow side walls of themold and there is adjusted the casting taper in accordance with a prede-8 termined reference-cooling rate value. The cooling surfaces of thenarrowand wide sides of the mold and which are associated with eachformat or shape are introduced into the computer 58, so that thespecific cooling rate can be continously calculated in Kcal per cm sec.

The computer 58 can also control the mechanical adjustment elements 60and 60' in accordance with random combinable programs of bothdifferential value signals 56, 57 and 56, 57'.

The described apparatuses for the accommodation of the casting taper ofthe narrow side walls, during the casting operation, to differentcasting parameters functions as follows: With a high output continuouscasting installation there should be cast, for instance, a sequence of anumber of pours. The strand format or shape amounts to 2,000 X 250 mm,the reference-casting speed 2 m/min and the maximum strand casting speed2.5 m/min. Prior to the start of casting there is adjusted to 0.9percent per meter the casting taper, converging in the direction ofcasting, of the hollow mold compartment between the narrow side walls inaccordance with the starting speed of l m/min, the strand width and thesteel quality. The aforementioned casting taper K in percent per meterper m) is calculated according to the following equation:

AB %Kperm L It is to be appreciated that the symbol AB constitutes thedifference in millimeters of the upper and the lower width of theconical hollow mold compartment 4, the symbol Bu the size in millimetersof the smaller width of the hollow mold compartment and the symbol L theheight in meters of the hollow mold compartment 4. After uncoupling thestarter bar, during the continuous pour or casting the casting tapershould be adjusted to a size which is associated with the referencestrand casting speed of 2 meters/min. For this purpose, prior to theadjustment operation, the clamping force which acts upon the wide sidewall 2' is reduced to about twice the value of the counterforce whichacts upon the wide side walls by means of the ferrostatic pressure. Thetaper of the narrow side walls is now simultaneously changed during theincrease of the casting speed to 2 meters/min so as to have a castingtaper or cone of 0.5 percent per meter. After such adjustment theclamping force is again increased to at least a five fold value of thecounterforce acting upon the wide side walls of the mold.

When using a mold according to the showing of FIGS. 3 and 4 there is notnecessary a reduction of the clamping force during the adjustment of thecasting taper.

In the case of molds which are equipped with devices for measuring thecooling rate at the narrow side walls, after accommodation of thecasting taper to the changed casting speed the actual-cooling rate valueof both narrow sides can be compared with the reference cooling ratevalue which has been predetermined to the altered casting speed. If theactual and reference values do not coincide, then by means of theobtained error or deviation signal it is possible to adjust the castingtaper at one or both narrow sides of the mold.

Further adjustments of the casting taper are for example necessary iffor some reason, for instance owing 9 to a leaky stopper, there must'becast during a certain time with the maximum casting speed of 2.5 m/min.Prior to termination of the casting operationthe casting speed isreduced in stages or stepsto about 0.81 m/min while accommodating thecasting taper to a value of O.8-O.9 per meter. I

If the casting taper is accommodated to a changed casting temperature,then such occurs in the same manner as for a change in the castingspeed. A higher casting temperature delays the solidification of thestrand shell in the mold similar to the situation where there is presenta higher casting speed. The cooling rate of the narrow side walls isthus increased. The accommodation of the casting taper thereforerequires, during increase of the casting temperature, a reduction in thetaper and during reduction of the casting temperature an increase of thetaper respectively.

The optimum casting taper or cone K (reference value) of the castingtaper during the casting operation can be determined as a function ofall of the effective casting parameters, such as casting speed, castingtmperature, strand format or shape, steel quality, nature of the castingpowder slag and so forth, in the following manner: If at a graph, suchas depicted in FIG. 6, there is plotted along the ordinate the coolingrate Q (Kcal/cm sec) and along the abscissa the taper K (in per m), thenat the region 80, with increasing taper K, there increases the coolingrate curve 85 from a taper which equals null to the higher cooling ratevalues, and then at the region 81 transforms into an approximatelyhorizontal curve. The optimum taper K (good cooling rate and relativelylittle wear) as a general rule is located at the transition curve at theregion 81 from the ascending to the horizontal curve branch at theregion or section 82. The illustrated curve 85 is only valid for oneexample, because depending upon the nature of the mold and the castingparameters the illustrated curve can deviate. By differentiating thedeviations (AQ/AK) there can be rapidly determined the sought for curveregion during the casting operation. By means of a computer connectedwith the continuous casting installation it is possible to alsoautomatically determine the optimum cooling rate as a function of thetaper while taking into account all casting parameters which act upon orinfluence the cooling rate.

Of course, it is to be mentioned that the invention is in no way to beconsidered as limited to the exemplary embodiments and examples. Themethod of this invention cannot only be carried out with the describedexemplary embodiments of apparatus but, it is for instance possible touse such method aspects also with molds which are not equipped with thedescribed plates 17, 31.

While there is shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto, but may be otherwise variously embodied and practicedwithin the scope of the following claims.

Accordingly, what is claimed is:

l. A method of controlling the cooling rate of the narrow side walls ofa plate mold during continuous casting, said plate mold furtherpossessing wide side walls, wherein the narrow side walls of the moldare fixedly clamped between the wide side walls of the '10 commodated tothe quality of the steel and the width of the strand, the improvementcomprising the steps of prior to startingthe casting operationadditionally adjusting the castingtaper to a reference valuecorresponding to at least oneprescribed casting parameter, and upondeviation of the casting parameter during the casting operation alteringthe casting taper according to predetermined reference values whichproduce a desired cooling effect and corresponding to such changingcasting parameter.

2. The method as defined in claim 1, including the step of using as thecasting parameter at least the casting speed.

3. The method as defined in claim 1, including the step of using as thecasting parameter at least the casting temperature.

4. The method as defined in claim 1, including the step of using as thecasting parameter both the casting speed and the casting temperature.

5. The method as defined in claim 1, including the step of continuouslymeasuring the cooling rate of the narrow side walls of the mold toobtain measurement values, comparing such measurement values with areference cooling rate value corresponding to an actual castingparameter, and upon the presence of a deviation between the referencecooling rate value and the actual cooling rate value altering thecasting taper until reaching the reference cooling rate value.

6. The method as defined in claim 5, wherein said actual castingparameter constitutes at least the actual casting speed.

7. The method as defined in claim 5, wherein said actual castingparameter constitutes at least the actual casting temperature.

8. The method as defined in claim 5, wherein said actual castingparameter constitutes at least both the actual casting speed and theactual casting temperature.

9. The method as defined in claim 1, including the step of continuouslymeasuring the specific cooling rate of the narrow and wide side walls ofthe mold to obtain measurement values, comparing such measurement valuesregarding the narrow and wide side walls of the mold, discriminating thespecific actual cooling rate ratio between such walls from apredetermined specific reference cooling rate ratio, and upon deviationbetween the specific reference cooling rate ratio and the actual coolingrate ratio altering the casting taper until reaching the specificreference cooling rate ratio.

10. The method as defined in claim 1, including the step of continuouslymeasuring the cooling rate of the narrow side walls of the mold, uponchange of the casting taper differentiating the deviation of the coolingrate after the deviation of the casting taper and determining areference taper which is associated with a reference cooling rate valuefrom the characteristics of a function curve, wherein the cooling rateis plotted as a function of the casting taper.

11. The method as defined in claim 10, including the step of selectingthe reference cooling rate value and the reference taper at a transitionregion between an ascending and horizontal branch of said functioncurve.

12. The method as defined in claim 1, including the step of maintainingthe size of the hollow mold compartment at the outlet end of the moldbetween the narrow side walls of the mold during accommodation of thecasting taper.

13. The method as defined in claim 1, including the step of reducing theforce required for fixedly clamping 12 sired cooling effect compriseselectively at least one of the following values: the casting taper inpercent per meter or a specific cooling rate of the strand.

15. The method as defined in claim 1, wherein said predeterminedreference values which produce a desired cooling effect comprise thecasting taper in percent per meter and a specific cooling rate of thestrand.

1. A method of controlling the cooling rate of the narrow side walls ofa plate mold during continuous casting, said plate mold furtherpossessing wide side walls, wherein the narrow side walls of the moldare fixedly clamped between the wide side walls of the mold, prior tothe start of the casting operation the hollow mold compartment isprovided between the narrow side walls with a casting taper whichconverges in the direction of travel of the cast strand and which isaccommodated to the quality of the steel and the width of the strand,the improvement comprising the steps of prior to starting the castingoperation additionally adjusting the casting taper to a reference valuecorresponding to at least one prescribed casting parameter, and upondeviation of the casting parameter during the casting operation alteringthe casting taper according to predetermined reference values whichproduce a desired cooling effect and corresponding to such changingcasting parameter.
 2. The method as defined in claim 1, including thestep of using as the casting parameter at least the casting speed. 3.The method as defined in claim 1, including the step of using as thecasting parameter at least the casting temperature.
 4. The method asdefined in claim 1, including the step of using as the casting parameterboth the casting speed and the casting temperature.
 5. The method asdefined in claim 1, including the step of continuously measuring thecooling rate of the narrow side walls of the mold to obtain measurementvalues, comparing such measurement values with a reference cooling ratevalue corresponding to an actual casting parameter, and upon thepresence of a deviation between the reference cooling rate value and theactual cooling rate value altering the casting taper until reaching thereference cooling rate value.
 6. The method as defined in claim 5,wherein said actual casting parameter constitutes at least the actualcasting speed.
 7. The method as defined in claim 5, wherein said actualcasting parameter constitutes at least the actual casting temperature.8. The method as defined in claim 5, wherein said actual castingparameter constitutes at least both the actual casting speed and theactual casting temperature.
 9. The method as defined in claim 1,including the step of continuously measuring the specific cooling rateof the narrow and wide side walls of the mold to obtain measurementvalues, comparing such measurement values regarding the narrow and wideside walls of the mold, discriminating the specific actual cooling rateratio between such walls from a predetermined specific reference coolingrate ratio, and upon deviation between the specific reference coolingrate ratio and the actual cooling rate ratio altering the casting taperuntil reaching the specific reference cooling rate ratio.
 10. The methodas defined in claim 1, including the step of continuously measuring thecooliNg rate of the narrow side walls of the mold, upon change of thecasting taper differentiating the deviation of the cooling rate afterthe deviation of the casting taper and determining a reference taperwhich is associated with a reference cooling rate value from thecharacteristics of a function curve, wherein the cooling rate is plottedas a function of the casting taper.
 11. The method as defined in claim10, including the step of selecting the reference cooling rate value andthe reference taper at a transition region between an ascending andhorizontal branch of said function curve.
 12. The method as defined inclaim 1, including the step of maintaining the size of the hollow moldcompartment at the outlet end of the mold between the narrow side wallsof the mold during accommodation of the casting taper.
 13. The method asdefined in claim 1, including the step of reducing the force requiredfor fixedly clamping the narrow side walls of the mold during theadjustment of the casting taper to about twice the value of acounterforce which is effective owing to the ferrostatic pressure of thecast steel, and after such adjustment again increasing such clampingforce to the value which prevailed prior to the adjustment.
 14. Themethod as defined in claim 1, wherein said predetermined referencevalues which produce a desired cooling effect comprise selectively atleast one of the following values: the casting taper in percent permeter or a specific cooling rate of the strand.
 15. The method asdefined in claim 1, wherein said predetermined reference values whichproduce a desired cooling effect comprise the casting taper in percentper meter and a specific cooling rate of the strand.